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CRISPR-Cas9 genome editing a 2-edged sword

CRISPR-Cas9 genome editing technology discovered in 2012 has revolutionized biological science and brought hope to millions of people born with incurable inherited killer diseases

In July 2018 the UK’s Nuffield Council on Bioethics endorsed the technology to make changes at the cell level in the human body that are heritable

This alarms bioethicists because there is no universally agreed regulation for CRISPR and the technology is cheap, easy-to-use and accessible and the line between “therapy” and “enhancement” is blurred

CRISPR was invented in the West but is rapidly being transformed into therapies in China where regulation is less than stringent

Will genome editing be used to enhance off-springs that satisfy parents’ preferences for children with specific characteristics?

CRISPR-Cas9 genome editing a 2-edged sword

The genie is out of the bottle!

On the 17th July 2018 the UK’s Nuffield Council on Bioethics published a report entitled, Genome Editing and Human Reproduction: Social and Ethical Issues, which concluded that germline editing, a process by which every cell in the human body could be altered in such a way that the change is heritable, is “morally permissibly” under certain circumstances. The Council was referring to developments of an invention made in 2012 by scientists Jennifer Doudna, and Emmanuelle Charpentier. They discovered how to exploit an oddity in the immune system of bacteria to edit genes, which resulted in CRISPR-Cas9, (an acronym for Clustered Regularly Interspaced Short Palindromic Repeats), which is generally considered the most important invention in the history of biology. Since its discovery, modified versions of the technology have found a widespread use to engineer genomes and to activate or to repress the expression of genes. Clinical studies testing CRISPR-Cas9 in humans are underway.

In this Commentary

In this Commentary we: (i) describe CRISPR-Cas9 and indicate how it has impacted medicine, biotechnology and agriculture, but suggest that it is most famous for its potential to modify human embryos to provide therapies for inherited killer diseases for which there are no known cures, (ii) suggest that although the technology is gaining regulatory support for its use in humans, there is no universal regulatory agreement. Some countries remain opposed to using CRISPR to edit human embryos while in China regulations is less than stringent. This patchy and loose state of affairs raise concerns among bioethicists, (iii) describe a non-profit agency that has significantly increased the accessibility of the technology, which has helped to democratise CRISPR, but also makes it easier for less stringently controlled laboratories to acquire it, (iv) briefly describe the Chinese scientists first use of the technology in humans and some of the unintended consequences which resulted. We provide examples of research that followed and briefly describe the US-China race to transform CRISPR into viable therapies, and suggest that China, helped by laxed regulation, is winning the race, (v) suggest that these factors, plus the fact CRISPR blurs the distinction between ‘therapy’ and ‘enhancement’, seems to convince bioethicists that the technology at some point in the future will be used to create ‘designer babies’, (vi) conclude by noting that for millennia people have been using radical and painful methods to modify their own and their children’s bodies and this seems to suggest that in time, germline editing will be perceived as a logical extension of these customs and practices, the genie is out the bottle and customize children are likely to become the norm.

CRISPR-Cas9

CRISPR is a mechanism deployed by bacteria to identify the DNA of invading viruses and is used by scientists to target a specific gene. Cas-9 is an enzyme, which acts like a pair of molecular scissors to cut out a piece of DNA and, if need be, replace it with a new gene. The process is faster, cheaper and easier to use than traditional genetic modification and has been likened to editing a Word document on a computer. Thus, gene editing has been taken away from highly skilled and tightly regulated molecular biologists and made more widely available. This not only democratizes science but also heightens ethical concerns.

CRISPR technologies impact medicine biotechnology and agriculture

Since the breakthrough was made in 2012, CRISPR-Cas9 has quickly development into a powerful, cheap and accessible tool in genetics. The technology is programmable, efficient, precise and scalable and has driven significant advances across medicine, biotechnology and agriculture throughout the world. As the world’s population and average temperatures increase, the demand for larger, more nutritious harvests and climate-adaptable crops will grow. The application of CRISPR technology to agriculture allows for an efficient and accurate mode of genetic manipulation to meet these increasing needs. The technology also has been used in the fight against malaria. According to a 2018 World Health Organization report, in 2016 there were 216m cases of malaria worldwide and 445,000 deaths from the disease. Malaria is spread by the female Anopheles-gambiae mosquito, which is one of 3,500 species of mosquitoes. Scientists have used CRISPR technology to edit the genes of this specific type of mosquito to avoid the malaria causing parasite. In a study carried out at Imperial College London and published in the September 2018 edition of Nature Biotechnology researchers succeeded in destroying a population of trapped Anopheles mosquitoes by using CRISPR technology to genetically alter cells to spread a genetic modification that blocks female reproduction so, over time, the malaria spreading Anopheles mosquitoes die out. The research demonstrates how a specific CRISPR application can propagate a particular suite of genes throughout an entire population or species and empower scientists in the war against diseases. “It provides hope in the fight against a disease that has plagued mankind for centuries,” says Andrea Crisanti, lead author of the Imperial study.

But the one application, which has made CRISPR famous is the modification of the human genome, which promises to cure some of the world’s deadliest diseases for which there are no known therapies. There are some 10,000 genetic diseases of which less than 6% have approved treatments.

Regulatory support

CRISPR genome editing technologies have been gaining regulatory acceptance for their use in humans and an increasing number of scientists in the US, UK and China have reached conclusions similar to those of the Nuffield Council, and suggest that if germline editing is shown to be safe and there are no medical alternatives, it should be permitted to prevent children being born with fatal diseases. In 2017, the UK’s Human Fertilization and Embryology Authority approved an application to use genome editing, which allows scientists to change an organism’s DNA in research on human embryos. Also, in 2017 a report from the US National Academy of Sciences(NAS) stated that clinical trials for editing-out heritable diseases could be permitted in the future for serious conditions under stringent oversight. At the same time as the Nuffield Council published its findings, - July 2018 - the US Food and Drug Administration (FDA) Commissioner Scott Gottlieb announced a new regulatory framework for genome editing for rare diseases. The following month, - August 2018 - the FDA along with the US National Institutes of Health (NIH) issued joint guidelines for a new streamlined process for assessing the safety of gene-therapy human clinical studies. And in an August 2018 New England Journal of Medicine editorialGottlieb and NIH Director Francis Collins argue that, “there is no longer sufficient evidence to claim that the risks of gene therapy are entirely unique and unpredictable - or that the field still requires special oversight that falls outside our existing framework for ensuring safety.”

No international regulatory framework for CRISPR triggers concerns

Despite increasing support for genome editing, to-date no internationally agreed regulatory framework exists that addresses the ensuing scientific, socio-ethical and legal challenges CRISPR technologies pose for regenerative and personalised medicine. Regulation is on a country-by-country basis and most nations struggle to assess whether gene editing may or may not be different from classical genetic engineering. Several nations remain opposed to the use of the technology in humans. The most contentious issue is human germline editing.

In Canada human germline editing is a criminal offence and sanctions range from fines of US$400,000 and up to ten years imprisonment. However, there is mounting pressure from Canadian scientists to change the law. France restricts genome editing research and supports the Oviedo Convention, which is the first multilateral binding instrument entirely devoted to bio-law. It came into force in 1999, backed by the Council for Europe and aims to prohibit the misuse of innovations in biomedicine. The treaty states that, “An intervention seeking to modify the human genome may only be undertaken for preventive, diagnostic, or therapeutic purposes and only if its aim is not to introduce any modification in the genome of any descendants”. In Germany germline editing is constrained by its 1990 Embryo Protection Act, which prohibits the generation and use of embryos for basic research, and also prohibits the harvesting of embryonic cells. South Korea’s Bioethics and Biosafety Act prohibits genetic experimentation, which modifies human embryos. Western observers suggest that regulation in China is “thin” and tends to be at the provincial and hospital levels. It has been reported that Chinese hospital review boards have approved clinical studies involving gene-editing and cancer patients without fully understanding the nature and power of the technology.

The “dark-side” of CRISPR technology

Weak regulation raises concerns about the level of ethical conduct in clinical studies and the potential dangers this holds for future therapies. Cognisant of CRISPR’s powerful capabilities, its relative cheapness and accessibility, (see below) James Clapper, the former US Director of National Intelligence describes CRISPR-Cas9 gene editing in the 2016 and 2017 Agency’s Worldwide Threat Assessment reports submitted to the US Congress as, “a potential weapon for mass destruction”. Jennifer Doudna,one of the inventors of CRISPR-Cas9 says that there are things which you would not want the technology used for and, “most of the public does not appreciate what is coming”. These sentiments resonate with bioethicists concerned about the absence of stringent universal regulation and the technology getting into the “wrong hands” and resulting in “designer babies”, an escalation of societal inequalities and increased safety and biosecurity issues.

Notwithstanding, many scientists view the ease of access to CRISPR technologies as a significant driver of cutting-edge research and the speed at which therapies for life-threatening diseases will enter clinics. The organization most responsible for CRISPR’s widespread accessibility is Addgene, a self-sustaining, non-profit plasmid repository, which facilitates the exchange of genetic material between laboratories throughout the world. (A plasmid is a small DNA molecule within a cell that is physically separated from a chromosomal DNA. It can replicate independently and is used in the laboratory manipulation of genes). It is free for scientists to deposit plasmids in Addgene and a nominal fee is charged for requests. This allows for maintenance and growth of the repository without reliance on grants or external funding. Founded in 2004, Addgene has significantly reduced the frustration scientists experience sharing plasmids with one another. The organization has developed into an important one-stop-shop for depositing, storing, and distributing plasmids globally and this has significantly enabled the democratization of CRISPR technologies. More than 6,300 CRISPR-related plasmids have been developed by over 330 academic laboratories throughout the world and deposited with Addgene. Since 2013, the organization has distributed over 100,000 CRISPR plasmids to some 3,400 laboratories in more than 75 countries.

Mixed results when CRISPR was first used in humans

CRISPR technology was first used in humans in China, when a group of scientists led by Junjiu Huang from Sun Yat-sen University in Guangzhou, attempted to modify the gene responsible for β-thalassemia, a potentially fatal blood disorder. Although the genomes of human embryos edited by the scientists could not be developed into a foetus, the researchers had difficulties publishing their findings because of ethical concerns. After being rejected by the journals Science and Nature their paper was published in 2015 in the journal Protein & Cell. The work triggered an international debate, but the research had a low success rate: only 4 of the 54 embryos that survived the technique carried the repaired genes. Huang and his colleagues identified two challenges. One was unintended genetic modifications - off target effects - when CRISPR either changes a gene scientist did not want changed or it fails to change a gene that they did. The second was that embryos, which did not get edited correctly mixed with those that did and became what is referred to as a “mosaic”.

New study discovers the deletion of thousands of DNA bases

Initially, these anomalies were thought to be minimal and improvements to the technique were thought to be able to reduce them so that they were virtually undetectable. Indeed, since 2015 the science of human genome editing has advanced significantly and there has been an explosion of research. In 2017 alone, there were some 3,500 research papers published on CRISPR technologies but concerns about CRISPR’s accuracy remain. During the past three years of intense research CRISPR-Cas9 became popularly perceived as a technique that can edit genetic code to correct defects inside individual cells and prevent and heal many intractable illnesses. Notwithstanding, also there has been a growing concern among scientists that because Cas9 enzymes reprogram the DNA of a cell, which is the fundamental building block for the development of an organism, the technique, if inaccurate, may cause more harm than good. Recent research supports this view. A study published in the July 2018 edition of the journal Nature Biotechnologydiscovered deletions of thousands of DNA bases, including at spots far from the edit. Some of the deletions can silence genes that should be active and activate genes that should be silent, including cancer-causing genes. This suggests that previous methods for detecting off-target mutations may have underestimated their true scale and therefore the potential for unintended consequences when using CRISPR technologies might be higher than originally thought. This finding poses a significant challenge for developing policy associated with CRISPR because you do not know what off-target effects will occur in humans until you use the technology.

Who is developing CRISPR-Cas9 therapies?

Notwithstanding, CRISPR–Cas9 is fast entering mainstream R&D and is perceived as a principal technology for treating diseases with a genetic basis and is increasingly playing a significant role in drug discovery. Scientists use the technology to either activate or inhibit genes and can determine the genes and proteins that cause or prevent specific diseases and thereby identify targets for potential therapies. Notwithstanding, drug development is a long and expensive process: it can take more than a decade and cost some US$2bn for researchers to move from the discovery of a target molecule to the production of a clinically approved therapy. So, it could be some time before the first drugs using CRISPR–Cas9 gene editing make it to the clinics. Notwithstanding, a lot has been achieved in a relatively short time.

Although CRISPR has proved its worth as a research tool, its use as a therapeutic is still uncertain. This is partly because the technology is so new there is a dearth of data upon which to base clinical evaluations. Notwithstanding, since Chinese scientists first used CRISPR to edit a human embryo's genome, new and more accurate variants of CRISPR have been developed. At about the same time - 2015 - that Huang published his findings using CRISPR for the first time in humans, two children with Acute Lymphoblastic Leukaemia, an incurable cancer, were treated at Great Ormond Street Hospital (GOSH) in London with a version of CRISPR called CAR-T cell therapy. This entails extracting blood cells from patients, then using CRISPR technologies to edit the T cells outside the body - ex vivo gene therapy - in order to transform the cells into enhanced cancer fighters before reintroducing them back into the patient’s blood stream. The treatment proved to be such a success that in 2018 CAR-T cell therapy was made available on the NHS. A US clinical study using the same technique started in August 2018 for people with Acute Lymphoblastic Leukaemia.

Over the past three years scientists in China have used newer versions of CRISPR to genetically engineer cells of at least 86 cancer and HIV patients. These cases form part of eleven human clinical studies using CRISPR-Cas9 technologies, ten of which are being undertaken in China. Another development of CRISPR is ‘base-editing’, which chemically modifies rather than cuts DNA. An August 2018 edition of the journal Molecular Therapy,describes how scientists in China used base editing, to remodel the DNA of human embryos to treat patients with the Marfan syndrome, which is a relatively common inherited connective tissue disorder with significant morbidity and mortality. A further milestone for the technology was reported 2018 when a study, led by Zheng Hu of the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, Guangdong, China, was the first to edit human cells while inside the body in an attempt to eliminate the human papilloma virus, which is the main cause of cervical cancer.

Company activity and clinical studies

Since the first publications in 2012 showcasing CRISPR-Cas9 as a gene editing tool, a number of companies have been set up to leverage the technology to develop innovative therapies. For example, Editas Medicine, was founded in 2013 by Feng Zhang, Jennifer Doudna, David Liu, George Church, and J.Keith Joung. However, just a few weeks after the company’s formation, Doudna stopped all involvement with Editas after Zhang was granted a number of CRISPR patents and issues concerning intellectual property began to appear. In October 2018 Editas filed an Investigational New Drug (IND) application with the US Food and Drug Administration (FDA) for a clinical study of a CRISPR genome editing medicine called EDIT-101 for the treatment of Leber Congenital Amaurosis type 10 (LCA10). This is a serious eye disorder that affects the retina, which is the specialized tissue at the back of the eye that detects light and colour. People with LCA10 typically have severe visual impairment from infancy.

In 2018 the European Patent Office granted Cellectis, a French biopharmaceutical company, the first patent to use CRISPR technology in human T cells.The patent will protect the application of CRISPR gene editing for T cell research until 2034, meaning every other company employing similar systems will need a license from Cellectis. Also, in 2018 CRISPR Therapeutics, co-founded by Emmanuelle Charpentier began a clinical study using CRISPR genome editing technologies and a similar ex vivo approach to target the blood disorder β-thalassemia. As yet no CRISPR therapies have reached the clinic.

US-China competition

There is intense and growing scientific competition between the US and China. Although CRISPR was invented in the West, it is more rapidly being transformed in China into therapies that can be used in clinics. An article in a January 2018 edition of the Wall Street Journalsuggests that regulation governing genome editing of human embryos in China is much less stringent than in the West where researchers have to pass muster with hospital review boards, ethics committees and government agencies before receiving approval. In China it is not unusual simply for hospital committees to give such permissions. According to Carl June, director of translational research at the Abramson Cancer Center, University of Pennsylvania and well-known for his research into T-cell therapies for the treatment of cancer, “We are at a dangerous point in losing our lead in biomedicine. It is hard to know what the ideal is between moving quickly and making sure patients are safe”. Western scientists believe that the less that stringent regulation in China gives Chinese researchers a significant competitive advantage in the race to get CRISPR therapies into clinics and bioethicists believe that loose regulation will result in unintended consequences that will harm patients and lead to “designer babies”, which could set-back the field for everyone.

Blurred line between therapy and enhancement

What makes regulation challenging is that CRISPR technologies blur the distinction between “therapy” and “enhancement”. Indeed, the 2018 Nuffield Council report referred to at the beginning of this Commentary suggests that such a distinction between therapy and enhancement cannot be expected to hold. Thus, it seems reasonable to assume that sometime in the future, CRISPR technologies, which are cheap, easy to use and accessible could be used to genetically enhance off-springs. In the first instance this solely might be focused on eradicating life-threatening diseases, but in the longer term it seems probable, especially in the absence of any universally agreed and tightly administered regulations, that genome editing will be used to create off-springs, which satisfy parents’ preferences for children with specific characteristics. Further, CRISPR technology is becoming popular among DIY scientists and biohackers – people who experiment on themselves - which exacerbates the concerns of bioethicists.

People have been radically altering bodies for millennia

Another reason to believe that germline editing will be used for ‘cosmetic’ enhancements rather than medical therapies is that for millennia people have used radical techniques to modify their own and their children’s bodies for cosmetic rather than therapeutic purposes. Here we illustrate the point with a few examples.

From the Song dynasties, which ruled China between 960 and 1279 until the early 20th century, the Chinese practiced the custom of breaking their first daughter’s toes and tightly binding them under the soles of their feet in order to stunt growth so that when the girl grew up she would walk diffidently, which was perceived as attractive. In England during the Victorian era between the mid 19th and the beginning of the 20th century, women, to make themselves attractive to men, corseted their bodies so tightly to create twelve-inch waists that their internal organs were redistributed with potentially dangerous consequences. Girls as young as 4 from the Kayan tribe of Myanmar use heavy brass coils to elongate their necks; a painful tradition dating back to the 11th century. The brass coils, that weigh an average of 10 kilos, deform their collar bones and neck and shoulder muscles. The Mursi tribe in Africa cut the lower lips of girls and insert plates to stretch the lips up to 12 cm in diameter.

In the 1970s and 1980s elective cosmetic surgical procedures gained popularity among wealthy people on the East and West coasts of America in order to enhance their appearance. The trend soon became global through the explosion of mass media. According to the International Society of Aesthetic Plastic Surgery in 2017 there was a 9% overall annual increase in surgical and nonsurgical cosmetic procedures globally. The US was the leader, accounting for 17.9% of all procedures. The top five countries were the US, Brazil, Japan, Italy and Mexico, which together accounted for 41.4% of all cosmetic surgical procedures worldwide. Russia, India, Turkey, Germany and France completed the top ten countries. In 2017, 400,000 American women elected to have breasts augmentation surgery; a 41% increase since 2000. About 1m rhinoplasties are carried out each year, with high volumes in Brazil and Mexico. The International Society of Aesthetic Plastic Surgery also reported that in 2016 surgeons in South Korea carried out the most cosmetic surgical procedures per capita: 20 per 1,000 people. V-shaped chins, with minimal jaw or cheekbone, round skulls, lifted lip corners, petite lips and slight puffiness under the eyes have been popular surgeries in South Korea, but recently the demand for such procedures has decreased while simpler and less invasive surgeries have increased. The Society also reported that labiaplasty showed the biggest (45%) increase since 2015. Lower body lift procedures increased by 29%, while upper body lift, breast augmentation using fat transfer, and buttock lifts increased by some 20%.

Such examples suggest that body enhancements, using a range of techniques, have been practiced in many cultures throughout the world for millennia. Thus, it seems reasonable to assume that in the absence of stringent regulation CRISPR will be perceived by some as just another enhancement technique.

Takeaways

The discovery of CRISPR Cas9 has revolutionized the way we think about developing therapies for the world’s deadliest diseases. This powerful technology has significant advantages over traditional medical technologies; it is cheap, easy-to-use and accessible, and these factors have helped to drive CRISPR’s global acceptance and use as a tool for new and innovative therapies. Over the past three years CRISPR R&D and clinical studies have developed at a pace and bring huge promise and significant hope to millions of people living with conditions with high rates of morbidity and mortality. Notwithstanding, bioethicists warn that with the absence of stringent universally agreed regulation, all these advantages could easily pivot into significant disadvantages and lead to parents enhancing the genetic composition of their children to make them taller, more intelligent etc. This could be a small step away from reigniting the ‘Charles Galton movement’. Galton was an English scholar and cousin of Charles Darwin. He lived during the Victorian era and died in 1911. Among other things, Galton studied anthropology and sociology and suggested that the elevated social position and heightened intelligence of the English upper classes and the criminality and lack of intelligence of the English under classes were all inherited traits and the result of superior and inferior genetic make-up respectively. According to Galton societies could be improved by selective breeding. Bioethicists are concerned that CRISPR technologies could be used for a 21st century version of Galtonism.